If a patient is afflicted with chronic bronchitis caused by breathing in harmful substances such as cigarette smoke over a long period of time, a medial wall of a bronchus may thicken due to inflammation, and the bronchus may become narrow. The amount of a secretion such as phlegm may increase due to chronic inflammation of the bronchus, and the secretion may stagnate in a stenosed site. If a substantial lumen of the bronchus, through which air is capable of flowing becomes narrow due to stenosis of the bronchus and the stagnation of a secretion, the flow of air is limited, and thus, normal breathing is disrupted.
A treatment method in which a stenosed site is widened using a medical device including a dilation portion, such as a balloon catheter, which can be dilated and deflated is known as a therapy method that is used in a case where a stenosed site is formed in a biological lumen such as a bronchus (refer to Japanese Patent Application No. JP-2011-56251).